Human OX40L (gp34, SwissProt P23510) is expressed on activated B cells and dendritic cells upon CD40/CD40L ligation, and on endothelial cells in inflammatory tissues (Review: Weinberg, A. D., Trends Immunol. 23 (2002) 102-109). It has first been isolated from HTLV-1 infected human leukemic cells (immortalization of these T-cells by generation of an autokrine loop with OX40). OX40L and antibodies against are mentioned e.g. in WO 95/12673; WO 95/21915; WO 99/15200; Baum, P. R., et al., EMBO J. 13 (1994) 3992-4001; Imura, A., et al., Blood 89 (1997) 2951-2958; Imura, A., et al., J. Exp. Med. 183 (1996) 2185-2195; Kjaergaard, J., et al., J. Immunol. 167 (2001) 6669-6677; Lane, P., J. Exp. Med. 191 (2000) 201-206; Mallett, S., and Barclay, A. N., Immunol. Today 12 (1991) 220-223; Mallet, S., et al., EMBO J. 9 (1990) 1063-1068; Ndhlovu, L. C., et al., J. Immunol. 167 (2001) 2991-2999; Ohshima, Y., et al., J. Immunol. 159 (1997) 3838-3848; Rogers, P. R., et al., Immunity 15 (2001) 445-455; Stüber, E., and Strober, W., J. Exp. Med. 183 (1996) 979-989; Stüber, E., et al., Gastroenterology 115 (1998) 1205-1215; Takahashi, Y., et al., J. Virol. 75 (2001) 6748-6757; Takasawa, N., et al., Jpn. J. Cancer Res. 92 (2001) 377-382; Taylor, L., and Schwarz, H., J. Immunol. Meth. 255 (2001) 67-72; Weinberg, A. D., et al., Nature Medicine 2 (1996) 183-189; Weinberg, A. D., et al., Semin. Immunol. 10 (1998) 471-480; Weinberg, A. D., Trends Immunol. 23 (2002) 102-109; Wu, T., et al., Transplant. Proc. 33 (2001) 217-218; Higgins, L. M., et al., J. Immunol. 162 (1999) 486-493; and Yoshioka, T., et al., Eur. J. Immunol. 30 (2000) 2815-2823. Human OX40L is the ligand for human OX40 (CD134) which is transiently expressed on activated CD4+ T cells. Engagement of OX40 by its ligand leads to a costimulatory signal for T cell activation. OX40/OX40L interaction is described to create a bidirectional signal (Matsumura, Y., et al., J. Immunol. 163 (1999) 3007-3011; Kotani, A., et al., Immunol. Lett. 84 (2002) 1-7). Further OX40/OX40L interaction mediate adhesion of activated T-cell to endothelial cells in inflammatory tissues. As OX40L is only transiently expressed on activated B cells, DC and endothelial cells, antibodies to OX40L should selectively block T cell activation and endothelial cell adhesion during an inflammatory response but leave unactivated, peripheral T cells unaffected. Yoshioka, A., et al. (Eur. J. Immunol. 30 (2000) 2815-2823) demonstrated the therapeutic potential of a neutralizing anti-mOX40L mAb in a mouse model for rheumatoid arthritis. Administration of it dramatically ameliorated the disease severity. This antibody showed similar activities in other related disease models, e.g. inflammatory skin disease, experimental autoimmune disease (EAE), GVHD, urine inflammatory bowel disease (Yoshioka, A., et al., Eur. J. Immunol 30 (1999) 2815-2823; Salek-Ardakani, S., et al., J. Exp. Med. 198 (2003) 315-324; Burgess, J. K., et al., J. Allergy Clin. Immunol. 113 (2004) 683-689; Hoshino, A., et al., Eur. J. Immunol. 33 (2003) 861-869; Arestides, R. S., et al., Eur. J Immunol. 32 (2002) 2874-2880; Nohara, C., et al., J. Immunol. 166 (2001) 2108-2115; Weinberg, A. D., et al., J. Immunol. 162 (1999) 1818-1826; Higgins, L. M., et al., J. Immunol. 162 (1999) 486-493; Humphreys, I. R., et al., J. Exp. Med. 198 (2003) 1237-1242; Akiba, H., et al., J. Exp. Med. 191 (2000) 375-380; Ishii, N., et al., Eur. J. Immunol. 33 (2003) 2372-2381; Blazar, B. R., et al., Blood 101 (2003) 3741-3748; Tsukada, N., et al., Blood 95 (2000) 2434-2439; Akiba, H., et al., Biochem. Biophys. Res. Commun. 251 (1998) 131-136.
Antibodies against OX40L have been investigated for their anti-inflammatory effects in various disease models (Sugamura, K., et al., Nat. Rev. Immunol. 4 (2004) 420-431). Tanaka, Y., et al, Int. J. Cancer 36, (1985) 549-555; Tozawa, H., et al., Int. J. Cancer 41 (1988) 231-238; and Miura, S., et al., Mol. Cell. Biol. 11 (1991) 1313-1325 describe mouse monoclonal antibodies named TARM-34 and TAG-34 that react with surface antigens of lines of human lymphocytes bearing a human T-cell leukemia virus type-I (HTLV-I). TAG-34 antibody is commercially available from MBL International Corporation. TAG-34 binds also to OX40L.